Titanic director James Cameron prepares for deep sea dive

James Cameron, the man behind water-logged blockbusters like Titanic and The Abyss, has announced his intention to dive alone to the deepest point in the ocean in the next few weeks and bring back some of the alien creatures that live there.

Cameron has already dived deeper than any other human on a solo mission, when he plummeted five miles down the New Britain Trench off Papua New Guinea during testing in his one-man seacraft earlier this week.

His next exploration is planned for the Mariana Trench's Challenger Deep, seven miles under the ocean, where bizarre alien forms no-one has ever seen before are thought to live, the National Geographic Society said in its magazine.

And he's not the only totally minted celeb attempting the trip. Richard Branson has also built a two-seater sub that he believes can make the Challenger Deep descent, although on the current timescale, it looks like Cameron will be first.

Humans have only been to the bottom of Challenger Deep once, back in 1960, when a two-man team went down in the US Navy submersible Trieste, but they could only stay there for 20 minutes and didn't see much because of the silt stirred up when they landed on the bottom.

Cameron, who is a National Geographic Explorer-in-Residence, is heading for the depths in his self-designed solo submersible Deepsea Challenger, which should give him around six hours on the seafloor.

Naturally, since it's Cameron, the whole thing will be captured for posterity in 3D with multiple high-def cameras, supported by an 8ft-tall array of LED lights. The sub will also be equipped with a robotic arm for snatching up rocks, animals and seafloor samples for study.

Cameron is hoping that the dive will answer some basic questions about ocean trenches, such as whether actual fish can live down there and what other strange species can survive in perpetual darkness in water chilled to near freezing.

"We're gonna go down there with our cameras, our lights, and find the answers to some of those questions," Cameron said.

Cameron built his mini-sub secretly in Australia over eight years and it is already the deepest-diving submersible in operation and the deepest-diving single-pilot one in history.

Deepsea Challenger is 24 feet tall, but just 12 metric tonnes, making it more than 10 times lighter than the last sub to visit the Mariana Trench, a feat achieved with a specially designed foam.

Despite its size, the trip is not going to be a comfy one for Cameron. The pilot's "sphere" is a 43-inch wide space where he can't even extend his arms or legs, and Cameron will be sharing that space with his food, a camera, joysticks and some warmer clothes.

"It's like a clown car in there," Cameron said. "You barely have room to get in, and then they hand you another 50 pounds of equipment."

The sub is also had to be designed to take the pressure it will experience on its seven-mile descent, when it will shrink by about 2.5 inches as the water pressure approaches 1,125kg per square centimetre.

"Every single fastener, every single way of joining structures on the sub had to be looked at very carefully, because otherwise stainless steel bolts would just shear as the sub compressed," Cameron said.

Once the sub is ready to resurface, Cameron will flip a switch and an electromagnetic system will jettison the heavy steel plates that allow it to sink, sending it bobbing to the surface.

Among the safety measures on the sub is a wire connecting the weights to the sub that will corrode in 12 hours if the weights don't disengage for any reason. If there's a power failure on the sub, the weights will also drop off, sending it back to the surface.

Despite these precautions, it will still be a dangerous trip.

Cameron said that he was a bit worried.

"Worry is a good thing when you're an explorer," he added. "I think when you're cavalier, when you take risk for granted - that's when you're going to get bitten."

You can see some pics of Cameron's Deepsea Challengerhere and a video announcing the trip to the Mariana Trench here. ®